CROSS REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. Application No. 61 /881 ,492 filed on September 24, 2013, the disclosure of which is incorporated herein by reference for all purposes.

BACKGROUND OF THE INVENTION - FIELD OF THE INVENTION

The present invention relates to a sand control apparatus and, more particularly, to a sand control apparatus for use in the production of heavy oils.

BACKGROUND OF THE INVENTION - DESCRIPTION OF PRIOR ART

In seeking to recover hydrocarbon-bearing fluids from subterranean formations, it is often the case that such fluids are found to reside in formations which are unconsolidated. Unconsolidated formations often comprise poorly cemented sandstone which have little or no cementing material holding the grains of sands together. The production of hydrocarbon from unconsolidated formations often results in the concomitant production of sand. As those skilled in the art readily appreciate, the production of sand is undesirable for many reasons, chief among them being that it is abrasive to the components within the well, such as tubing, pumps, valves or the like, causing rapid erosion of such equipment and, in addition, may result in the partial or complete blockage of the well. Sand control can be particularly acute in the case of the production of heavy oil. Heavy crude oil is any type of crude oil which does not easily flow. It is referred to heavy because its density or specific gravity is heavier than that of light crude oil.

It is estimated that the reserves of heavy crude oil in the world are more than twice those of conventional light crude. For example, it is estimated that the Orinoco deposits in Venezuela contains a recoverable value of 513 billion barrels making this area one of the world's largest recoverable oil deposits.

It is known that frictional drag force is exerted on formation sand grains created by the flow of reservoir fluid. The frictional drag force is directly related to the velocity of fluid flow and the viscosity of the reservoir flow being produced. Thus, high reservoir fluid viscosity will apply a greater frictional drag force to the formation sand grains than will reservoir fluid with a low viscosity. The influence of viscous drag causes sand to be produced from heavy oil reservoirs, which contain low gravity, high viscosity oils, even at low flow velocities.

In the production of oil, including heavy crude oil, a variety of different generic filter or screen systems are currently used, such as simple, slotted liners, wire wrapped pre-packed screens, excluders, equalizing con slot screens, and special strata pack membrane screens. Slotted liners are typically pieces of casing into the walls of which have been cut precisely sized slots which can be keyhole shaped but which are designed to exclude sand and other contaminates from entering the interior of the slotted liner. When designing a slotted liner, the goal is to provide optimum slot characteristics to effectively remove the solids from the produced hydrocarbons and minimize the opportunity for the slots to plug over the lifetime of a well. Typically, slots can range in width from 0.010" up to 0.250". The slots are usually between 1 .5" and 2" long. Per industry standards, the slots provide 3% open area per lineal foot of productive zone of wellbore. The production of slotted liners is time consuming and expensive. For example, it is estimated that it takes at least one hour to slot at least one joint of 7" liner.

It is well known that the slots can rust such that build up will cause or severely diminish the open area of a slot. Furthermore, 95% of slots fill when they are being forced into the formation.

When the slotted liners plug either because of sand or rust, they must be pulled from the formation and generally replaced.

SUMMARY OF THE INVENTION

In one aspect, the present invention provides a sand exclusion apparatus for use in the production of oil, particularly, heavy crude oil.

In another aspect, the present invention provides a sand exclusion apparatus for use in the production of crude oil which can be reused if it is pulled from the well because of plugging or other failure.

In still another aspect, the present invention provides a method of manufacturing a sand exclusion apparatus for use in the production of crude oil, particularly heavy crude oil.

These and further features and advantages of the present invention will become apparent from the following detailed description, wherein reference is made to the figures in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a schematic, sectional view of part of a prior art downhole filter, the filter being shown located in a wellbore.

Fig. 2 is an enlarged schematic sectional view taken along the line 1— 1 of Fig. 1 .

Fig. 3 is a flyer showing a commercially available slotted liner typically used in sand control operations.

Fig. 3A is a cross-sectional view taken along the lines 3— 3 of Fig. 3.

Fig. 4 is an elevational view of a portion of a sand control apparatus in accordance with the present invention.

Fig. 5 is a partial sectional view of the sand control apparatus shown in

Fig. 4.

Fig. 6 is a view, similar to Fig. 5, showing an insert with multiple openings. Fig.7 is a partial sectional view, similar to Fig. 5 but showing another form of insert used in the sand control apparatus of the present invention.

Fig. 8 is a cross-sectional view taken along the lines 8— 8 of Fig. 7.

Fig. 9 is a partial sectional view, similar to Fig. 7 but showing another embodiment of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring first to Fig. 1 , there is shown a schematic, sectional view of a prior art sand control device in the form of a section of a tubular member, e.g., a liner 10. The liner 10 is shown as being located in a wellbore 12 which has been drilled from surface to intersect a sand-producing hydrocarbon-bearing formation 14. As seen the liner 10 comprises a metal tubular, e.g., a casing joint, in which a large number of longitudinally extending slots 16 have been cut. In the embodiment shown in Fig. 1 , the slots have a keystone or trapezoidal form, i.e., the width of the slot increases from the exterior of the tubular wall W ₀ to the interior Wi . This feature is shown in Fig. 2 which is an enlarged sectional view of a slot 16 through line 1— 1 of Fig. 1 . As shown, the inner slot width Wi is greater than the outer slot width W ₀ . The outer, maximum width W ₀ is selected to be smaller than the diameter of the particulates it is desired to prevent from passing from the formation 14, through the tubular wall 18 and into the tubular bore 20. Those of skill in the art will of course realize that the dimensions of the slot 16 have been exaggerated.

Referring to Fig. 3, there is shown a typical commercial slotted liner comprised of a tubular member 20 having a box end 22 and a pin end 24, there being formed a plurality of slotted openings 26 along the length and around the periphery of tubular member 20.

Referring now to Fig. 4, there is shown an embodiment of the present invention. The sand exclusion device of Fig. 4, shown generally as 30 comprises a tubular section 32 having a cylindrical wall 33 and a box connection 34 at one end and a pin connection 36 at the opposite end there being formed a plurality of longitudinal and circumferentially spaced perforations in the wall 33 of tubular section 32. Received in the perforations are inserts or buttons 40. Although as shown, the buttons 40 have a single opening or slot 42, it will be apparent that the buttons or inserts could have more than a single opening. In this respect, reference is now made to Fig. 6 which shows a fragmentary view similar to Fig. 5 of a button 44 which has two slots 46.

Referring now to Figs. 7 and 8, there is shown another embodiment of the present invention. In the embodiment shown in Fig. 7, rather than having slots running along the diameter of the button, the button, shown generally as 50 in Fig. 7, has a series of radially outwardly projecting, circumferentially spaced lobes 52, the lobes 52 engaging the walls of the perforation 38 in the wall of the tubular member 32. As can be seen, the lobes 52 serve to form a series of circumferentially spaced, arcuate slots 54 between the wall 33 of the tubular member 32 and button 50.

Preferably, the buttons of the present invention are removably received in the holes in the tubular sections so as to be easily replaced if necessary. Furthermore, while the buttons are shown as being generally circular, it will be understood that they could be of various other shapes. Additionally, other shaped slots or openings through the buttons can be used.

The advantage of the embodiment shown in Figs. 7 and 8 resides in the ease of manufacture of the buttons 50. In this regard, the buttons could be cut out of a plate, e.g., a metal plate, by laser, water jet or the like which would eliminate the more expensive method of machining the straight slots in the buttons 42 and 44 shown in Figs. 4-6. They could also be formed by stamping the inserts out of a plate.

In forming the sand exclusion apparatus of the present invention, it will be recognized by those skilled in the art that it can be constructed much more easily than the typical slotted liners of the prior art. It is estimated that it takes approximately one hour and costs $14,000 to $15,000 to slot a typical 7" liner. Also, manufacture of the slotted liners requires specialized machining techniques and/or expensive laser cutting tools. Furthermore, depending upon the particle size of the sand, a particular slotted liner must be employed such that the slot size matches the particle size.

This often requires that a variety of slotted liners with slots of different sizes be located at the well site in order that the proper size slotted liner is available when needed.

Using the sand exclusion device of the present invention, one can easily construct the basic liner portion simply by drilling holes in the liner which is, as well known to those skilled in the art, a simple machining operation. Furthermore, the drilled holes can have the same or different diameter but can be virtually of any size so long as the structural integrity of the liner is not compromised.

The buttons can have slots or openings, e.g. cut-outs as shown in Figs. 7 and 8, be they arcuate, straight, circular, etc. of varying sizes. Accordingly, for a given well site, it may only be necessary to supply a single liner drilled with holes and a supply of buttons or inserts with various size slots or openings to accommodate the particular well conditions. Obviously this cuts down on inventory in terms of the number of liners that must be at the well site. This also leads to another advantage in that if it is desired that the liner have openings of varying size, it is only necessary to use buttons having one sized opening or slot in some of the holes and buttons having other sized openings or slots in other of the holes. Thus for example, the lower part of the liner may be provided with buttons wherein the slots are of one size and the upper portion of the liner may be provided with buttons having slots of a larger or smaller size as necessary. This is a clear advantage over the use of different sized screens which are often used in connection with slotted liners to obtain proper sand control. It will also be appreciated that the liner, e.g., the tubular member, which carries the openings can have holes of varying sizes to accommodate the specific needs of the formation in which the liner is placed. Indeed, the ability to vary (1 ) the number, shape and size of openings in the buttons, (2) the number, shape, and size of the buttons, and (3) the number, shape, and size of the perforations in the tubulars themselves, allows for the design of a specific sand control apparatus for specific formations needs. It will be understood that the inserts will have a size and shape generally complementary to the perforations so that they can be secured in the perforations.

Another advantage of the present invention is that if it is necessary to pull the sand exclusion apparatus of the present invention from the hole because of plugging, it is only necessary to replace the buttons as opposed to attempting to clean out a typical slotted liner or replace it with a new slotted liner.

The buttons can be press fitted into the holes of the liner, threaded into the holes of the liner, or a J-slot type connection can be employed. As noted, the buttons are preferably removably secured in the perforations.

Typically heavy oil reserves are found in unconsolidated sand stone reservoirs that necessarily require some form of sand exclusion strategy across the reservoir as well as at the lateral main bore junction interface. In heavy oil sand, effective sand control strategies must be carefully planned since one of the difficult problems to address in heavy oil sand control targets is their natural tendency to suspend formation solids, often referred to as basic solids and water solids. Because the sand exclusion apparatus of the present invention can be made much cheaper, provides versatility at the well site without the need to inventory numerous different slotted liners, it offers distinct advantages in connection with production of heavy oil.

Although specific embodiments of the invention have been described herein in some detail, this has been done solely for the purposes of explaining the various aspects of the invention, and is not intended to limit the scope of the invention as defined in the claims which follow. Those skilled in the art will understand that the embodiment shown and described is exemplary, and various other substitutions, alterations and modifications, including but not limited to those design alternatives specifically discussed herein, may be made in the practice of the invention without departing from its scope.